The present invention relates to a machining apparatus, and more particularly, to a stepless speed change bench drill.
Presently, various bench drills being available in the market all employ a tower-type belt pulley to regulate the rotating speed thereof. When requiring changing the speed, the drill has to be stopped to open the belt housing, then the belt is moved from one groove to another groove of the belt pulley so as to increase or decrease the speed. Such speed regulation has disadvantages that the operation is complicated and unsafe, and the efficiency is low. In addition, due to the limit of the groove of the tower pulley, only step speed change such as 5 speeds and 12 speeds can be achieved. In order to achieve the stepless speed change, the skilled person in the art have made great efforts to design the stepless speed change bench drill. The Chinese patent No. 97206964.X disclosed a stepless speed change bench drill. However, since this bench drill is complicated in the speed regulation structure and limited in the range of the speed regulation, it has not been produced really. The same applicant of the present invention applied a stepless speed change bench drill and a speed regulation device in March 2001 and June 2001 respectively. Though stepless speed regulation is achieved and there are a plurality of advantages, it is tested by a number of experiments recently that the bench drill and the speed regulation device still have some shortcomings that continuous speed change and uninterrupted speed change can not be achieved, the accuracy of the speed change and the self locking state after speed change are not good enough, so that it is difficult to meet the requirements of exiguous speed change.
An object of the invention is to provide a stepless speed change bench drill, which has the following advantages: the operation of the speed change is simple, short-cut and labor saving, the drill does not need to be stopped at the time of speed change, the speed change is accurate, the effect of the self locking after speed change is good, and it can meet the requirements of constant power within the largest range of the speed change and can achieve continuous and uninterrupted speed change.
The above and other objects of the invention is accomplished by providing a stepless speed change bench drill comprising a pedestal, a vertical post mounted on the pedestal, a worktable and a cabinet mounted on the vertical post, a driving shaft and a main shaft which are mounted on the upper portion of the cabinet, a motor for transmitting power to the driving shaft, a motor movable wheel and a motor stationary wheel which are mounted on the driving shaft, and a main shaft movable wheel and a main shaft stationary wheel which are mounted on the main shaft, wherein a speed regulation device is provided between the driving shaft and the main shaft, the speed regulation device comprises a speed regulation shaft provided with a threaded section, the threaded section is engaged with a threaded hole formed on a bearing block, the bearing block is simultaneously mounted on the main shaft, the speed regulation shaft is rotated by a speed regulation hand wheel.
A driven bevel gear is mounted on the lower end of the speed regulation shaft, the driven bevel gear is engaged with a driving bevel gear, the speed regulation hand wheel is fixedly connected to the driving bevel gear.
A threaded hole and an unthreaded hole are provided on the bearing block.
A groove is provided on the edge of the main shaft stationary wheel.
A digital display sensor is mounted on the edge of the main shaft stationary wheel, the digital display sensor is connected to a printed circuit board via a lead, and a digital display screen is connected to the printed circuit board.
A switch box is mounted on the cabinet, and the display screen is mounted on the switch box.
A shifting fork body is mounted on the speed regulation shaft of the speed regulation device, the shifting fork body is connected to the speed regulation shaft via thread, the lower shifting fork of the shifting fork body may be formed integrally with the shifting fork body, the upper shifting fork is mounted on the upper end of the shifting fork body by fastener.
The speed regulation device further comprises a transition means mounted between the driving shaft and the speed regulation shaft, the transition means comprises a middle shaft mounted on the cabinet, a lower movable wheel, a stationary wheel set and an upper movable wheel which are mounted on the middle shaft, a belt is provided between the driving shaft and the middle shaft, and between the middle and main shaft is also provided a belt.
The upper shifting fork of the shifting fork body on the speed regulation device is mounted on an upper bearing block, the lower shifting fork of the shifting fork body is mounted on a lower bearing block.
A digital display sensor is mounted on the outer edge of the main shaft stationary wheel, the digital display sensor is connected to a printed circuit board via a lead, a digital display screen is connected to the printed circuit board.
This invention has the following advantages tested by a number of experiments. The operation of the speed change is simple, short-cut and labor saving, the drill does not need to be stop at the time of speed change, the speed change is accurate, the effect of the self locking after speed change is good, and it can meet the requirements of constant power within the largest range of the speed change and can achieve continuous speed change and uninterrupted speed change. The speed regulation can be displayed accurately, the speed regulation hand wheel can regulate the speed within a range of more than 360 degrees. And the production cost thereof is low.